AVR Guardian filters out dogs

Cats and dogs can get along quite nicely when they are raised up together. The problem with this type of arrangement tends to be keeping dogs out of the cat box and away from the cat food. [Ryan Meuth] tried out a simple electronic barrier to keep the dog away. It uses an IR transmitter and receiver to shine a beam of invisible light across the doorway to his cat room. In the demo after the break you’ll see that he took steps to make sure the cats don’t set off the alarm. The beam of light is set high enough that their bodies don’t get in the way, and the firmware measures the amount of time the beam was broken in order to avoid false positives caused by the cats’ tails. If the dog does try to get into the room it will break the beam and set off a high-pitched alarm sound.

It’s interesting that the dog doesn’t like the sound but the cat’s don’t seem to be scared of it. Also, we’ve got a less-than-ferocious feline that would love to chew on the cord that connects the two modules. Still, it’s a solution that works for [Ryan] and could be incorporated into an automatic feeder to keep the dog away from feedings while you’re out of the house.

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PIC based picture frame

Take a PIC 24HJ256GP206 processor and add a dash of knock-off touchscreen and a pinch of SD card compatibility for a DIY digital picture frame. [Daniel] wrote his own driver for the HX8347 controlled LCD that can achieve 15 FPS at 320×240 resolution with 16-bit color. As this was a gift for his wife, [Daniel] included a heart-shaped ring of LEDs that fade in and out like an electronic pulse. He notes that the JPEG decoder runs rather slow but that’s mostly because of the bottleneck caused when accessing data from the SD card. We’ve got more pictures and a link to the source code after the break.

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Nixie Sudoku: a look at the hardware

We’re always happy to receive a tour of the guts that make things work. [John Sarik] posted several pictures and descriptions of the hardware that makes up his Nixie Sudoku build. The modular design uses professionally made circuit boards which greatly improve the durability of a large set of circuits such as this.

The design draws on good ideas from similar hardware. The Nixie Duo kit from Ogi Lumen allows tubes to be mounted on top of driver boards with cascading shift registers for control of up to 8 tubes. The ArduiNIX shield makes the high voltages needed for Nixies easy to control with an Arduino. No, [John] didn’t just order these kits and plug them into each other. He designed his own boards to suit his needs. Each driver board can control 9 tubes in a 3×3 grid, all on one PCB. His high voltage board can supply enough juice for the whole system which is tied together with a single Arduino board.

His writeup is quite interesting so do take a look. He also filmed a walk through video which we’ve embedded after the break. It clears up some questions, such as showing the use of a blinking decimal point to indicate the current cursor position.

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Android Development 101- Part 2:Graphical Elements

In this tutorial, we will be continuing from where we left off with the “hello world” application.  This time adding a graphical user interface (GUI) and a “toast”. The GUI will consist of a button, textbox and a label. The “toast” will be issued onto the screen when the button is pressed.

Some may wonder what a toast is.  Well, for non-programmers, a toast is a text notification that for the most part is used only to display an error on the screen (I am a big fan of using toasts instead of an alert on the screen as its less intrusive).  For this article we will use a toast to display a message on the screen that will take the text in the textbox and issue a “Hello Greg” onto the bottom of the screen.  After this article completed you will be able to successfully make toast commands, design the layout of the hello world program, and pull text from a textbox.

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Xbox 360 hard drive adapter (redux)

[Chlazza] let us know about their Xbox hard drive to SATA adapter, allowing the use of an Xbox 360 (original) hard drive on a PC without voiding the drive’s warranty. Looking for a fun and enriching experience read: really bored and inspired by a previous adapter we featured, [Chlazza] set out to make their own and ended up succeeding with a board that costs less than $1 in parts. Of course the drive uses its own Fat32 based file system so there is still some hacking to do if you intended to read the data, but this is a step in the right direction.